Blowers for household and small appliances
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- INST FUER LUFT & KAELTETECHNIK GEMEINNUETZIGE GMBH
- Filing Date
- 2018-09-28
- Publication Date
- 2026-07-09
AI Technical Summary
Existing counter-rotating fans in household and small appliances suffer from limited air throughput and pressure build-up due to their axial design, leading to noise emissions.
A counter-rotating blower with a diagonal and axial impeller configuration, where the first impeller is designed as a diagonal fan and the second as an axial fan, with a housing that guides the flow to minimize twist and turbulence, and can be driven by separate or shared motors, ensuring a twist-free gas flow exit.
Enhances air throughput and pressure build-up while reducing noise emissions by optimizing the geometric design and operational control of the impellers, allowing for efficient and quiet operation.
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[0001] The invention relates to a blower for household and small appliances with two counter-rotating impeller wheels, which is particularly suitable for use in vacuum cleaners, table fans, hair dryers, hand dryers and the like; the invention also relates to methods for operating the blower.
[0002] Due to the particular advantages of turbomachinery with counter-rotating rotors in terms of size, speed, and noise emission, these machines have become established in almost all areas of technology. For example, blowers, propellers, or compressors with axially arranged impeller wheels are known from US 3,083,893 A, US 5,931,640 A, DE 10 2007 022 663 A1, DE 10 2011 053 787 A1, or DE 10 2015 111 291 A1.
[0003] Counter-rotating fans are still less common in household appliances and small devices, although they have already been described for this purpose. For example, EP 1 653 087 A1 discloses a counter-rotating fan for cooling electronic devices, and JP 2013-177832 A discloses a counter-rotating table fan.
[0004] These well-known counter-rotating blowers for household and small appliances have two axially arranged impeller wheels in the design of axial fans.
[0005] However, pressure build-up and airflow are technically limited in axial fans.
[0006] It is therefore an object of the invention to provide a counter-rotating blower for household and small appliances which, compared to blowers with impeller wheels in the design as axial fans, enables a higher airflow and a higher pressure build-up with a largely swirl-free, axial exit of the gas flow from the blower.
[0007] This problem is solved by a blower for household and small appliances with the characterizing features according to claim 1 and by methods for operating the blower according to claims 8 to 10; advantageous further developments of the blower are described in dependent claims 2 to 7.
[0008] According to the invention, the blower for household and small appliances comprises a first impeller, a second, counter-rotating impeller arranged axially behind the first impeller, and a housing with flow guidance adapted to the geometry of the impellers surrounding the impellers, wherein the first impeller has the design of a diagonal fan and the second impeller has the design of an axial fan.
[0009] The counter-rotating drive of the two impeller wheels draws in gases, in the simplest case air, axially at the inlet of the blower, i.e. at the inlet of the first impeller wheel, and allows them to flow axially out at the outlet of the blower, i.e. at the outlet of the second impeller wheel, for further use.
[0010] An advantage of the combination of counter-rotating impellers according to the invention is that a higher pressure build-up can be achieved by the first impeller in the design as a diagonal fan, and the radially acting flow components as well as the swirl of the flow can be completely or at least largely compensated by the flow guidance of the housing and the subsequent counter-rotating impeller in the design as an axial fan, so that the gas flow leaves the outlet of the blower almost without swirl.
[0011] Furthermore, to achieve the same airflow performance as blowers with two axial fans, the blower can be operated at a lower speed, thus simultaneously reducing noise emissions. In household appliances and small appliances, the blower therefore contributes to the desired reduction of disruptive noise emanating from these devices.
[0012] According to the invention, different variants are possible for an electric motor drive of the impeller wheels: For example, both impeller wheels can each be driven by a separate electric motor assigned to the respective impeller wheel.
[0013] Furthermore, the impeller wheels can be driven by a common electric motor, which is designed as an external rotor with double winding for two separate, opposing directions of rotation.
[0014] Furthermore, it is possible that the first impeller is connected to an inner shaft and the second impeller is connected to an outer shaft arranged coaxially to the inner shaft and rotating in the opposite direction, with the inner shaft and the outer shaft being coupled and driven by means of an electric motor with inductive power transmission.
[0015] In one embodiment of the blower, the inlet angle of the impeller blades of the second impeller is designed such that, at constant rotational speed of the impellers, the velocity vector of the absolute flow velocity at the outlet of the first impeller corresponds to the addition of the velocity vector of the relative flow velocity at the inlet of the second impeller and the velocity vector of the circumferential velocity at the inlet of the second impeller.
[0016] Furthermore, it can be provided that the exit angle of the impeller blades of the second impeller is designed such that, at constant rotational speed of the impellers, the velocity vector of the absolute flow velocity at the exit of the second impeller corresponds to the sum of the velocity vector of the relative flow velocity at the exit of the second impeller and the velocity vector of the circumferential velocity at the exit of the second impeller, wherein the magnitude of the circumferential component of the velocity vector of the absolute flow velocity at the exit of the second impeller is zero.
[0017] Furthermore, the geometry of the impeller blades of the first impeller can be designed such that, at constant rotational speed of the impellers, the magnitude of the circumferential velocity at the inlet of the first impeller is smaller than the magnitude of the circumferential velocity at the outlet of the first impeller, wherein the magnitude of the circumferential component of the absolute flow velocity at the outlet of the first impeller is greater than the magnitude of the circumferential component of the absolute flow velocity at the inlet of the first impeller.
[0018] In a further embodiment of the blower, the geometry of the impeller blades is designed such that, at a constant rotational speed of the impeller blades, the magnitude of the circumferential component of the absolute flow velocity at the outlet of the first impeller blade is equal to the magnitude of the circumferential component of the absolute flow velocity at the inlet of the second impeller blade.
[0019] It may also be provided that the geometry of the impeller blades is designed such that, at constant rotational speed of the impeller blades, the circumferential component of the absolute flow velocity at the inlet of the second impeller blade is opposite to the circumferential velocity at the inlet of the second impeller blade.
[0020] The advantage of these different designs regarding the geometric shape of the impeller blades lies in ensuring a virtually swirl-free airflow. Avoiding turbulence allows for optimal airflow to downstream components, such as annular nozzles. Furthermore, the static efficiency of the fan increases due to the conversion of dynamic energy into static energy.
[0021] In addition to the design of the impeller blades, the blower can be operated with the aim of achieving a swirl-free outflow by selectively controlling the rotational speeds of the two impeller wheels, for example by means of a control device.
[0022] In a first embodiment of the method for operating the blower according to the invention, the impeller wheels are driven at such speeds that the velocity vector of the absolute flow velocity at the outlet of the first impeller wheel corresponds to the addition of the velocity vector of the relative flow velocity at the inlet of the second impeller wheel and the velocity vector of the circumferential velocity at the inlet of the second impeller wheel.
[0023] It can further be provided that the impeller wheels are driven at such rotational speeds that the velocity vector of the absolute flow velocity at the outlet of the second impeller wheel corresponds to the sum of the velocity vector of the relative flow velocity at the outlet of the second impeller wheel and the velocity vector of the circumferential velocity at the outlet of the second impeller wheel, wherein the magnitude of the circumferential component of the velocity vector of the absolute flow velocity at the outlet of the second impeller wheel is zero.
[0024] Furthermore, the blower can be operated in such a way that the impeller wheels are driven at such speeds that the magnitude of the circumferential velocity at the inlet of the first impeller wheel is less than the magnitude of the circumferential velocity at the outlet of the first impeller wheel, wherein the magnitude of the circumferential component of the absolute flow velocity at the outlet of the first impeller wheel is greater than the magnitude of the circumferential component of the absolute flow velocity at the inlet of the first impeller wheel.
[0025] In another embodiment of the method for operating a blower, the impeller wheels are driven at such speeds that the magnitude of the circumferential component of the absolute flow velocity at the outlet of the first impeller wheel is equal to the magnitude of the circumferential component of the absolute flow velocity at the inlet of the second impeller wheel.
[0026] Finally, the blower can be operated in such a way that the impeller wheels are driven at such speeds that the circumferential component of the absolute flow velocity at the inlet of the second impeller wheel is opposite to the circumferential velocity at the inlet of the second impeller wheel.
[0027] The use of the blower according to the invention is particularly suitable for household appliances with high suction or blowing power, such as vacuum cleaners or hand dryers, but also for table fans or hair dryers.
[0028] The invention is explained in more detail below with reference to exemplary embodiments and the schematic drawings. These show: Fig. 1: the blower with a subsequent ring nozzle, Fig. 2: the blower, driven by an electric motor with inductive power transmission, Fig. 3: the blower, driven by an electric motor in the form of an external rotor with double winding, Fig. 4: the blower, driven by two separate electric motors, Fig. 5: the velocity vectors in the flow field.
[0029] The blower according to the Fig. 1 has the first impeller 1 in diagonal fan design and the second impeller 2 in axial fan design. Both rotate in opposite directions as intended (see arrows on the impeller blades). 1 , 2 ). Both impeller wheels 1 , 2 are from the case 11 with the flow guidance 10 surrounded.
[0030] In the exemplary embodiment, air, visualized by the flow arrows with wave-like stylization, is drawn in via the unlabeled intake tract, passes through the blower and flows into the unlabeled ring nozzle behind the blower outlet.
[0031] The blower after the Fig. 2 is equipped with an electric motor with inductive power transmission 12 , which is connected via the electrical connection 9 is connected to the electrical power supply, powered.
[0032] The inflow 3 of the first impeller 1 and the outflow 4 from the second impeller 2 These are in turn represented by flow arrows with a wave-like stylization; the gas flow takes place within the flow guide. 10 of the case 11 .
[0033] The first impeller 1 is with the wave 8(Inner shaft) connected and rotates together with it. The shaft bearing 8 This is done via the warehouses 5 in fixed struts 6 .
[0034] The (unlabeled) outer shaft, which connects the windings 7 The electric motor's components are coaxial on the shaft. 8 (Inner shaft) mounted.
[0035] The blower after the Fig. 3 has for both impeller wheels 1 , 2 a common electric motor designed as an external rotor, wherein the impeller wheels 1 , 2 on the central, standing axis 8 rotate. The counter-rotation is achieved through the double winding. 7 This ensures two separate, opposing directions of rotation. The other reference symbols correspond to those of the Fig. 1.
[0036] Regarding the blowers according to the Fig. 4 are the first impeller 1 and the second impeller2 Each is driven by a separate electric motor. The reference symbols correspond to those of the Fig. 1.
[0037] The Fig. Figure 5 illustrates the velocity vectors at different positions of the blower, using the example of a swirl-free flow approaching the first impeller. 1 , namely at the entrance 1.1 of the first impeller 1 , at the exit 1.2 of the first impeller 1 , at the entrance 2.1 of the second impeller 2 and at the exit 2.1 of the second impeller 2 . With u is the peripheral speed of the respective impeller 1 , 2 , with w being the relative velocity of the flow in the moving system of the impeller 1 , 2and where c denotes the absolute velocity of the flow in the stationary system. The velocities at the inlet of the first impeller are designated according to the aforementioned positions of the blower. 1 with u'1 , w'1 or c'1 , the velocities at the exit of the first impeller 1 with u'2 , w'2 or c'2 , the speeds at the entrance of the second impeller 2 with u"1 , w"1 or c"1 , and the speeds at the exit of the second impeller 2 with u"2 , w"2 or c"2 The velocity vectors are represented by arrows with solid lines; for the absolute velocity c The components of the velocity in the circumferential and axial directions, represented by a dashed line, are indicated at two positions in the flow ( c'2u , c'2m , c"1u , c"1m ). Designations for other circumferential and axial components of the velocity vectors not shown in the figures are derived accordingly.
[0038] In the left half of the image Fig. Figure 5 shows a stylized representation of the channel cross-section with an arrow indicating the flow; the right half of the image also shows stylized cross-sectional representations of the impeller blade profiles. 1 , 2 shown. Reference symbol list 1 first impeller, diagonal fan 1.1 Entry of the first impeller 1.2 Exit of the first impeller 2 second impeller, axial fan 2.1 Entry of the second impeller 2.2 Exit of the second impeller 3. Inflow 4. Outflow 5 bearings 6 strut 7 windings (electric motor) 8 Shaft or axle 9 electrical connection 10 Flow guidance 11 cases 12 inductive power transmission u peripheral speed of the respective impeller w Relative velocity of the flow in the moving system of the impeller c Absolute velocity of the flow in the stationary system c u Circumferential component of the absolute velocity c m Axial component of the absolute velocity u'1, w'1, c'1 Velocities at the entrance of the first impeller u'2, w'2, c'2 Velocities at the exit of the first impeller u"1, w"1, c"1 Velocities at the inlet of the second impeller u"2, w"2, c"2 Velocities at the outlet of the second impeller QUOTES INCLUDED IN THE DESCRIPTION
[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature
[0000] US 3083893 A
[0002] US 5931640 A
[0002] DE 102007022663 A1
[0002] DE 102011053787 A1
[0002] DE 102015111291 A1
[0002] EP 1653087 A1
[0003] JP 2013177832 A
[0003]
Claims
[1] Blower for household and small appliances, comprising a first impeller (1), a second counter-rotating impeller (2) arranged axially behind the first impeller (1) and a housing (11) adapted to the geometry of the impellers (1, 2) surrounding the impellers (1, 2) with flow guide (10), characterized by , that the first impeller (1) has the design of a diagonal fan and the second impeller (2) has the design of an axial fan. [2] Blower according to claim 1, characterized by , that - the impeller wheels (1, 2) are each driven by a separate electric motor assigned to the respective impeller wheel (1, 2), or - the impeller wheels (1, 2) are driven by a common electric motor, which is designed as an external rotor with double winding (7) for two separate, counter-rotating directions of rotation, or - the first impeller (1) is connected to an inner shaft and the second impeller (2) is connected to an outer shaft arranged coaxially to the inner shaft and rotating in the opposite direction, wherein the inner shaft and the outer shaft are coupled and driven by means of an electric motor with an inductive power transmission (12). [3] Blower according to claim 1 or 2, characterized by , that the inlet angle of the impeller blades of the second impeller (2) is designed such that, at constant rotational speed of the impellers (1, 2), the velocity vector of the absolute flow velocity (c'2) at the outlet (1.2) of the first impeller (1) corresponds to the addition of the velocity vector of the relative flow velocity (w"1) at the inlet (2.1) of the second impeller (2) and the velocity vector of the circumferential velocity (u"1) at the inlet (2.1) of the second impeller (2). [4] Blower according to claim 1 or 2, characterized by, that the exit angle of the impeller blades of the second impeller (2) is designed such that, at constant rotational speed of the impellers (1, 2), the velocity vector of the absolute flow velocity (c"2) at the exit (2.2) of the second impeller (2) corresponds to the sum of the velocity vector of the relative flow velocity (w"2) at the exit (2.2) of the second impeller (2) and the velocity vector of the circumferential velocity (u"2) at the exit (2.2) of the second impeller (2), wherein the magnitude of the circumferential component (c"2) u ) of the velocity vector of the absolute flow velocity (c"2) at the outlet (2.2) of the second impeller (2) is equal to zero. [5] Blower according to claim 1 or 2, characterized by, that the geometry of the impeller blades of the first impeller (1) is designed such that, at constant rotational speed of the impellers (1, 2), the magnitude of the circumferential velocity (u'1) at the inlet (1.1) of the first impeller (1) is less than the magnitude of the circumferential velocity (u"2) at the outlet (1.2) of the first impeller (1), wherein the magnitude of the circumferential component (c'2) u ) the absolute flow velocity (c'2) at the outlet (1.2) of the first impeller (1) is greater than the magnitude of the circumferential component (c'1) u ) the absolute flow velocity (c'1) at the inlet (1.1) of the first impeller (1). [6] Blower according to claim 1 or 2, characterized by , that the geometry of the impeller blades of the impeller wheels (1, 2) is designed such that at constant rotational speed of the impeller wheels (1, 2) the magnitude of the circumferential component (c'2 u) the absolute flow velocity (c'2) at the outlet (1.2) of the first impeller (1) is equal to the magnitude of the circumferential component (c"1 u ) the absolute flow velocity (c"1) at the inlet (2.1) of the second impeller (2). [7] Blower according to claim 1 or 2, characterized by , that the geometry of the impeller blades of the impeller wheels (1, 2) is designed such that at constant rotational speed of the impeller wheels (1, 2) the circumferential component(c"1 u ) the absolute flow velocity (c"1) at the inlet (2.1) of the second impeller (2) is opposite to the circumferential velocity (u"1) at the inlet (2.1) of the second impeller (2). [8] Method for operating a blower according to claim 1 or 2, characterized by, that the impeller wheels (1, 2) are driven at such rotational speeds that the velocity vector of the absolute flow velocity (c'2) at the outlet (1.2) of the first impeller wheel (1) corresponds to the addition of the velocity vector of the relative flow velocity (w"1) at the inlet (2.1) of the second impeller wheel (2) and the velocity vector of the circumferential velocity (u"1) at the inlet (2.1) of the second impeller wheel (2). [9] Method for operating a blower according to claim 1 or 2, characterized by, that the impeller wheels (1, 2) are driven at such rotational speeds that the velocity vector of the absolute flow velocity (c"2) at the outlet (2.2) of the second impeller wheel (2) corresponds to the addition of the velocity vector of the relative flow velocity (w"2) at the outlet (2.2) of the second impeller wheel (2) and the velocity vector of the circumferential velocity (u"2) at the outlet (2.2) of the second impeller wheel (2), wherein the magnitude of the circumferential component (c"2 u ) of the velocity vector of the absolute flow velocity (c"2) at the outlet (2.2) of the second impeller (2) is equal to zero. [10] Method for operating a blower according to claim 1 or 2, characterized by, that the impeller wheels (1, 2) are driven at such rotational speeds that the magnitude of the circumferential velocity (u'1) at the inlet (1.1) of the first impeller wheel (1) is less than the magnitude of the circumferential velocity (u'2) at the outlet (1.2) of the first impeller wheel (1), wherein the magnitude of the circumferential component (c'2) u ) the absolute flow velocity (c'2) at the outlet (1.2) of the first impeller (1) is equal to the magnitude of the circumferential component (c'1) u ) the absolute flow velocity (c'1) at the inlet (1.1) of the first impeller (1).